South America's top 4 most contaminated water basins

- Monday, August 12, 2013

Many of South America’s rivers and lakes are severely contaminated due to untreated industrial waste and sewerage being dumped directly into their waters.  In many cases the contaminated water basins are also a major source of potable water, leading to health issues and environmental concerns.

BNamericas takes a look at the top 4 most contaminated water basins, based on the projected cost of clean-up, and the plans in action to remediate them.

Tietê River (Brazil, US$4.57bn)

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The Tietê river, which runs 1010km from east to west across the country's largest city, São Paulo, suffers from industrial pollution and untreated domestic wastewater.

A 25-year, five-phase initiative to clean-up the river started in 1995, with the aim of reaching 100% sewage collection and treatment coverage throughout the 28 municipalities of the São Paulo metropolitan region.

The total estimated cost to clean-up the river is US$4.57bn, with US$1.1bn already spent on phase I and US$500mn spent on phase II.

The US$1.05bn phase III is currently underway with a focus on expanding wastewater collection and treatment services to prevent further pollution. Specifically, works include installing 1,250km of wastewater pipeline, 580km of collector trunk and interceptor pipeline and 200,000 sewer system connections in addition to expanding and implementing new wastewater treatment plants.

The US$1.92bn phase IV is set to kick-off at the end of 2013 with works expected to wrap up by 2020.

Matanza-Riachuelo River (Argentina, US$4.29bn)

The waters of the Matanza-Riachuelo river, which flows through the Buenos Aires province, have been described as black and rancid, the result of both domestic and industrial waste being discharged into the river without further treatment.

In 2008 the country's supreme court ordered the national government to remediate the Matanza-Riachuelo basin, and in 2010 river basin authority Acumar estimated that the total cost of clean-up could reach 23.8bn pesos (US$4.29bn) until 2024.

AySa, the state water utility active in Argentine capital Buenos Aires, is currently carrying out a US$1.49bn program to clean-up the basin, partially financed through a US$840mn loan from the World Bank. The program includes five major components, only two of which have been tendered to date, while the tenders for the 794mn-peso (US$143mn) Dock Sud wastewater pretreatment plant, the Sudoeste 304mn-peso sludge treatment plant and seven aeration systems along the Riachuelo river have been called but are yet to be awarded.

Lake Ypacaraí (Paraguay, US$1.5bn)

Lake Ypacaraí, located east of capital Asunción, is contaminated by uncontrolled dumping of waste and wastewater, and consumption of the water by neighboring areas as well as recreational activity in the lake were shut down last year.

Public works and communications ministry (MOPC) estimates that US$1.5bn over the next 15-20 years is needed to rehabilitate the country's sewerage system and ameliorate the contamination of the Lake Ypacaraí basin

MOPC is currently developing a three-step strategy to rehabilitate the Ypacaraí lake basin based on improving the water quality alongside tracking and sanctioning.

In particular, MOPC plans to destine US$100mn annually to upgrading the sewerage systems in the cities surrounding the lake basin.

Bogotá river basin (Colombia, US$1.1bn)

The Bogotá river runs over 150km through the Cundinamarca department, where it is contaminated by both untreated sewage and industrial wastewater.

In 2010 Colombian authorities estimated that at least US$1.1bn would be needed to clean up the river basin by 2030.

Currently, the Cundinamarca Autonomous Corporation (CAR), which is in charge of carrying out environmental programs in Colombia's central Cundinamarca region, is implementing a US$487mn program to overhaul the Bogotá river basin. The program includes a US$335mn project to upgrade Bogotá's major wastewater treatment plant El Salitre in addition to flood control and river restoration works for another US$140mn.